I applied online after speaking with a recruiter at a career fair. I had an on-campus interview and then proceeded to final round interviews during their "University Day." The process was fairly quick, and the recruiters made me feel welcome during the tour of Facebook. There was a presentation about what an internship at Facebook is like, followed by lunch from their cafeteria. Each candidate had their own individual interviewer and was taken to one of the many rooms in the building for their interview. There were two interviews in total before a decision was given.

Verify a binary search tree.